Since 1981, still video photography has found its market value for its instant result, easy transfer, computer process, and relatively high image resolution. Such images can be picked up by an image sensing device like CCDs and stored or recorded in a medium in either analog form or digital form. Further, it can be reproduced through a monitor or printer and the like and even transmitted to a remote place without losing much resolution of the images. Thus, it is used for various purposes, such as industrial design, documentation, museums or showroom display and so on. However, the resolution of the still video image is still limited in comparison with the still film image. Also, the still video image is very easy to be modified or altered by means of computer or other apparatus. Therefore, it cannot be used for documentation sometimes. In fact, both of the still film image and the still video image cannot be substituted for one another. Accordingly, it becomes desirable to have a camera which can capture both of the images.
To fulfill those demands and to provide a convenient and economic way of capturing such wonderful images, a number of photographic systems and equipments have been developed. Among those, still video and motion video combined camcorder and still video back adaptor for conventional film camera are main trends in the development of such equipments, taking respective advantages of electronic view finder of the motion video and simplicity of the structure of the film camera. Some of double function cameras are described in U.S. Pat. Nos. 4,862,280 and 4,829,384. Both of them are granted to Iida et al.. There are two imaging lenses facing the same object scene and one objective lens provided in the patents of Iida et al. thereby constructing a still camera unit and video camera unit in one system to shoot the same object scene. It is also suggested that the electronic view finder is interchangeable with the optical system for simply changing the way of viewing. However, the two unit structure is relatively complex.
It is known in the art that in a single lens reflex camera an object image is formed on a focusing screen by the light which passes through an objective lens and is reflected by a reflex mirror to the focusing screen. The object image is then inverted by a pentagonal roof prism to a non-inverted image which is observed by a user through an eye-piece lens.
Therefore, there are several patents which utilize the image formed on the focusing screen for different purposes. As described in U.S. Pat. No. 4,894,723 to Takaiwa et al., an image sensing apparatus is provided on the focusing screen to pick-up image which is in turn recorded and measured, and to provide control signals, such as aperture value, upon the measuring result so as to show correct image on an electronic view finder or mini-monitor. Another U.S. Pat. No. 4,855,837 to Tanimoto et al. utilizes the image on the focusing screen to serve for a relay optical system or relay finder optical system; while an attachable still video back can replace the convetional film back for taking still video picture.
Further, U.S. Pat. No. 4,303,322 to Someya et al. teaches the use of an electronic image pick-up device attachable to a single lens reflex camera at a receptacle in place of an optical finder unit so that the image thus picked up can be connected to a display device or video tape recorder for remote monitoring and recording. Another U.S. Pat. No. 4,757,388 to Someya et al. shows a camera having built-in CCDs or the like in a position optically equivalent to the film, i.e. the focusing screen. Thus, an electronic view finder is provided in place of an optical finder which enables a user to view the object scene in the finder from either the rear or the front of the camera.
As discussed hereinabove, none of the patents discloses a camera which is simple in structure but enables to take pictures in both film and still video images either simultaneously or respectively.
As discussed hereinabove, none of the patents discloses a camera which is simple in structure but enables to take pictures in both film and still video images either simultaneously or respectively.